1590s, "to run off," probably from Middle Dutch (ont)lopen "run away," from ont- "away from" (from Proto-Germanic *und- which also gave the first element in until) + lopen "to run," from Proto-Germanic *hlaupan (source also of Old English hleapan; see leap (v.)). Sense of "run away in defiance of parental authority to marry secretly" is 19c.

In support of this OED compares Old English uðleapan, "the technical word for the 'escaping' of a thief." However there is an Anglo-French aloper "run away from a husband with one's lover" (mid-14c.) which complicates this etymology; perhaps it is a modification of the Middle Dutch word, with Old French es-, or it is a compound of that and Middle English lepen "run, leap" (see leap (v.)).

The oldest Germanic word for "wedding" is represented by Old English brydlop (cognates: Old High German bruthlauft, Old Norse bruðhlaup), literally "bride run," the conducting of the woman to her new home. Related: Eloped; eloping.